Department of Biology, Plant Physiology, Faculty of Science, Lorestan University, Khoramabad-Tehran Road (5th K), Iran.
Department of Biology, Plant Physiology, Faculty of Science, Lorestan University, Khoramabad-Tehran Road (5th K), Iran; and Corresponding author. Emails:
Funct Plant Biol. 2019 Mar;46(4):360-375. doi: 10.1071/FP18076.
Zinc oxide nanoparticles (NPs) are the third highest in terms of global production among the various inorganic nanoparticles, and there are concerns because of their worldwide availability and accumulation in the environment. In contrast, zinc is an essential element in plant growth and metabolism, and ZnO NPs (nano-ZnO) may have unknown interactions with plants due to their small sizes as well as their particular chemical and physical characteristics. The present study examined the effect of nano-ZnO (25nm) and bulk or natural form (<1000nm, bulk-ZnO), compared with zinc in the ionic form (ZnSO4) on Nicotiana tabacum seedlings in a nutrient solution supplemented with either nano-ZnO, bulk-ZnO (0.2, 1, 5 and 25µM) or ZnSO4 (control) for 21 days. Results showed that nano-ZnO at most of the levels and 1µM bulk-ZnO positively affected growth (root and shoot length/dry weight), leaf surface area and its metabolites (auxin, phenolic compounds, flavonoids), leaf enzymatic activities (CAT, APX, SOD, POX, GPX, PPO and PAL) and anatomical properties (root, stem, cortex and central cylinder diameters), while bulk-ZnO caused decreases at other levels. The activities of enzymes were induced to a greater extent by intermediate nano-ZnO levels than by extreme concentrations, and were higher in nano-ZnO treated than in bulk treated tobacco. As the ZnO level increased, the vascular expansion and cell wall thickening of the collenchyma/parenchyma cells occurred, which was more pronounced when treated by NPs than by its counterpart. The Zn content of root and leaf increased in most of ZnO treatments, whereas the Fe content of leaves decreased. Our findings indicate that tobacco responded positively to 1µM bulk-ZnO and to nearly all nano-ZnO levels (with the best levels being at 0.2µM and 1µM) by morphological, physiological and anatomical adjustments.
氧化锌纳米粒子（NPs）是全球无机纳米粒子中产量第三高的，由于其在全球范围内的可用性和在环境中的积累，人们对此表示担忧。相比之下，锌是植物生长和新陈代谢所必需的元素，而 ZnO NPs（纳米 ZnO）由于其较小的尺寸以及特殊的化学和物理特性，可能与植物发生未知的相互作用。本研究在营养液中添加纳米 ZnO（25nm）和块状或天然形式（<1000nm，块状 ZnO）以及离子形式的锌（ZnSO4），比较了纳米 ZnO（25nm）和块状 ZnO（0.2、1、5 和 25µM）对烟草幼苗的影响，以及 ZnSO4（对照）处理 21 天。结果表明，大多数浓度的纳米 ZnO 和 1µM 块状 ZnO 均能促进生长（根和茎的长度/干重）、叶片表面积及其代谢物（生长素、酚类化合物、类黄酮）、叶片酶活性（CAT、APX、SOD、POX、GPX、PPO 和 PAL）和解剖特性（根、茎、皮层和中央圆柱直径），而块状 ZnO 在其他水平则会降低。中间浓度的纳米 ZnO 比极端浓度更能诱导酶的活性，并且在纳米 ZnO 处理的烟草中，酶的活性比在块状 ZnO 处理的烟草中更高。随着 ZnO 浓度的增加，厚角组织/薄壁组织细胞的维管束扩张和细胞壁增厚，纳米 ZnO 处理比其相应物处理更为明显。大多数 ZnO 处理均增加了根和叶的 Zn 含量，而叶片的 Fe 含量则降低。我们的研究结果表明，烟草对 1µM 块状 ZnO 和近所有纳米 ZnO 水平（最佳水平为 0.2µM 和 1µM）做出了积极的响应，表现为形态、生理和解剖学上的调整。
